Plant and Pollinator Matchmakers: Naturalist Notes
As summer peaks we can still see insects flying from flower to flower doing their thing. This “thing” not only feeds them, but helps the plants - pollination! Pollination is pollen grains being moved from the anther, the male part of the flower, to the stigma, the female part. Once this transfer happens it allows the plant to reproduce, producing seeds and fruit. While the relationship between pollinating critters and plants is vital to life on this planet, the evolution of their relationship is fascinating!
There are many different pollinators that include many insects, some birds, and even a couple of mammals. A healthy ecosystem depends on these animals because, at minimum, 75% of all the world’s flowering plants rely on pollinators to reproduce. These plants stabilize soils to stop erosion, clean air, provide oxygen, purify water, and support other wildlife. Of the nearly 190,000 different types of plants that depend on pollinators, more than 1,200 of those are agricultural corps. That breaks down to 1 out of every 3 bites of food you eat exists because of pollinators!
Now, how do these pollinators know what plants need them for pollination? Well, the honest answer is the animal doing the pollination doesn’t care about that, they are just trying to get a meal of either nectar or pollen. The plants have evolved to attract these animals so they will move their pollen around. Most pollination occurs by accident. Pollen grains stick to an insect’s body or the fur of a mammal, then when it moves to the next flower, some of the pollen falls off and it’s transferred to the stigma. Different flower characteristics make this interaction more successful. These characteristics are called pollinator syndromes, and these syndromes can help identify what kind of pollinator will visit that plant.
Knowing the different pollinator syndromes helps when we want to attract certain animals to our gardens. Six of the basic pollinator syndrome traits are color, odor, nectar, pollen, flower shape, and nectar guides. Nectar guides are markings of low ultraviolet (UV) reflectance on each petal that is concentrated in the flower’s center. These guides help the pollinators that can see in UV locate the flower’s center more quickly. Flowers that use nectar guides mainly attract bees and some butterflies to pollinate them.
Some of the main pollinators are bees, butterflies, moths, flies, beetles, bats, and birds. They benefit from their adaptations to a particular flower because it ensures that there will be a constant supply of food with less competition. The plant and the pollinator have a mutually beneficial relationship. Let’s look at how the main pollinators differ from one another in the types of flowers they are looking for:
Bees like flowers that are bright white, yellow, blue, or UV. The flower needs to have nectar guides, a fresh mild pleasant odor, nectar, and a limited supply of soft, scented pollen. The flower itself needs to have a large landing platform and is usually shallow.
Butterflies are attracted to flowers that are bright in colors like reds and purples and are in the shape of a narrow tube with a wide landing pad. The flower does not need to have a strong scent. There should be nectar guides for butterflies and an ample amount of nectar that is hidden deep in the flower. There does not need to be a lot of pollen to attract butterflies.
Moths like similar flowers to butterflies in shape, nectar, and pollen, but differ in some other traits. Moths need a flower that is pale red, purple, pink, or white and it needs to emit a strong, sweet odor at night. Moths do not need nectar guides.
Flies are different from bees, butterflies, and moths. They like flowers that are pale and dull to brown or purple and are flecked with translucent patches. These flowers have to have a putrid odor. They do not need the flower to have nectar guides or even nectar, but there should be a modest amount of pollen. The shape of the flower can be shallow, funnel-like, or a complex trap.
Bats and beetles share a lot of similar characteristics in the flowers they are attracted to. Both like dull green or white flowers that do not have nectar guides and are bowl-like in shape. Bats like flowers that are closed during the day and open at night. Both prefer flowers with ample amounts of pollen. Where bats and beetles differ is in odor and nectar. Beetles like flowers that smell strongly fruity, putrid, or completely odorless depending on the species. Bats prefer flowers with a strong musty smell that emanates at night. Beetles like flowers where nectar is sometimes present, but not hidden. Bats require flowers that have an abundance of nectar that is somewhat hidden.
One of the last groups of pollinators is birds. They like large funnel or cup-shaped flowers with a strong perch. These flowers need an ample supply of nectar that is deeply hidden, but having nectar guides or an odor is unnecessary. Birds prefer scarlet, orange, or white flowers that have a modest amount of pollen.
Pollinators can still be found on flowers that don’t match these characteristics, but it might not be the most successful interaction for either the flower or critter.
How flowers and pollinators co-evolved to depend on each other is incredible. All animal and plant life, including humans, directly depend on these transactions and adaptations. Over years there has been a decline in our pollinators, but there is a lot you can do to help. Consider planting native plants that attract these pollinators, letting your grass grow for some time (no-mow May!), avoiding pesticide use, and letting leaves sit in the fall are all ways you can help restore our pollinator populations. If you want to see some of the plants that benefit from pollinators up close, come to the Johnson Nature Center’s Walking Salad Tour scheduled on July 16th!
Submitted by Cathy Wesley, Naturalist, June 2022